1. Field of the Invention
The present invention relates to a portable device preferably applied to, for example, a mobile phone device, especially relates to a portable device provided with a fuel cell system as an electric power supply.
2. Description of the Related Art
In recent years, the usage of a fuel cell system as an electric power supply in a portable device such as a mobile phone device has been suggested, and fuel cells of this type have been developed. In a mobile phone device, since functions such as a television-broadcasting viewing function and an audio playback function are mounted, the amount of electric power used in the device is likely to increase, leading to a study for mounting a fuel cell system to prolong the duration of a power supply.
The fuel cell system generates electric power by a reaction of a fuel with oxygen in the air, which are both fed to the fuel cell. Fuel cells are grouped into a passive type or an active type depending on a difference in the process for feeding the fuel to the fuel cell.
The passive fuel cell system has a simple configuration and a high efficiency in power generation efficiency because the fuel and air are statically fed by utilizing a concentration gradient, diffusion, and capillary transport without power for transporting the fuel and air, leading to a low cost. However, the passive fuel cell system has following disadvantages: generated electric power and output density are low; it takes a long start-up time to generate enough amount of electric power; and electric power generation may not be immediately stopped.
The active fuel cell system has following advantages by virtue of the fuel fed from a fuel tank by an auxiliary unit such as a pump and a fan: it takes a short start-up time; and it has high output density. However, the active fuel cell system takes a high cost due to many components such as the auxiliary unit, and the power generation efficiency is lowered due to power to drive the auxiliary unit.
In addition, the active fuel cell system utilizes a secondary cell as an electric power supply in order to drive the auxiliary unit until the fuel cell begins to generate electric power. On the other hand, since the auxiliary unit may not be driven when the secondary cell is run out, the fuel may not be fed, so that electric power may not be generated.
Thus, although the secondary cell is charged by an external electric power supply when the secondary cell is run out, it is troublesome and inconvenient to carry an electric power supply such as an AC adapter only for this charging at any time. In order to avoid this problem, it is suggested, for example, that a solar cell be additionally provided as an auxiliary electric power supply, and that the auxiliary unit be driven by the solar cell when the residual power of the secondary cell is low, so that the fuel is fed to generate electric power.
FIG. 6 shows a configuration example of the mobile phone device in this case. A mobile phone device 10 is configured in a case 11 having a square shape. A display, an operation section, a microphone, and a loudspeaker, which function as the mobile phone device, are disposed on the rear surface (downside in FIG. 6, not shown). On a surface which is the upper side in FIG. 6, fuel cell-air inlets 12 are provided, in the approximately two-thirds of the space on a front side, and a solar cell 13 is provided in the approximately one-third of the space on a back side. As shown in FIG. 6, the fuel cell-air inlets 12 are vertically and horizontally disposed in series.
A fuel cell 20 is disposed inside the case 11 at a position corresponding to a position at which the fuel cell-air inlets 12 are disposed. The fuel cell 20 includes an air electrode 21, an electrolyte film 22, and a fuel electrode 23. The fuel cell-air inlets 12 are connected to the air electrode 21. In addition, a fuel tank is omitted in FIG. 6.
The configuration shown in FIG. 6 allows the mobile phone device to include the fuel cell system and the solar cell as the electric power supply. The fuel can be fed to the fuel cell by utilizing the output from the solar cell in cases where, for example, the residual power of an incorporated secondary cell is run out. Japanese Unexamined Patent Application Publication No. 2007-207661 discloses an example of the configuration of an electric power supply combining a fuel cell system and a solar cell.